Excavator door latching means



Oct. 23, 1962 w. P. ATKINSON ETAL 3,059,793

EXCAVATOR DOOR LATCHING MEANS Filed Nov. 27. 1959 5 Sheets-Sheet 1" Fla! - INVENTORS =l WILLIAM F. Arxmsere Bnurqo L.|,o--ena- ATTOR EY Oct. 23, 1962 w. P. ATKINSON ETALY 3,059,793

EXCAVATOR 000R LATCl-IING MEANS Filed Nov. 27, 1959 s Sheets-Sheet 2 Fla '2 INVENTORS WILLIAM F. ATKINSON BRUNO L. .LoN-eneN BY M M ATT NEY Oct. 23, 1962 w. P. ATKINSON ETAL. 3,059,793

EXCAVATOR DOOR LATCHING MEANS Filed Nov. 27. 1959 3 Sheets-Sheet 3 INVENTORS WILLIAM F. ATKINSON BY BRUNO L.Lo--sa5- ATTORNEY United States Patent Ofilice 3,059,793 EXCAVATGR DG'IBR LATCHING MEANS William I. Atkinson and Bruno L. Lonngren, South Milwaukee, Wis, assignors to Bueyrus-Erie Company, South Milwaukee, Wis, a corporation of Delaware Filed Nov. 27, I959, Ser. No. 855,799 Claims. (tCl. 2114-4146) This invention relates to the dipper door of an eX- cavating shovel and more particularly to the means for holding the door in a closed position.

Conventional excavator dippers normally have a swing ing door hinged at the rear of the dipper and a latch fixed to the front of the door to hold the door in a closed position. The latch usually comprises a bar or a bolt adapted to be received in a keeper plate secured to the front of the dipper. Since the front portion of the dipper encounters most of the resistance to movement during digging operation, a latch mechanism at the front of the dipper door is subjected to maximum wear and damage. Consequently, a latch mechanism so constructed and located must be frequently repaired or replaced. Such a latch mechanism also offers additional resistance to the movement of the dipper during digging and represents a parasitic drag in relation to the total force required to raise the dipper during digging operations. In addition to these disadvantages, the conventional latch bar and keeper mechanism frequently become fouled with dirt or other foreign material which prevents the latch from operating properly.

Accordingly, it is an object of this invention to provide an excavator dipper having a door hinged at the rear thereof with door-restraining means adjacent the rear of the door and thereby eliminate the conventional latch bar and keeper at the front of the dipper.

A further object of the invention is to provide a dipper door with a restraining means which does not require a power-operated means to close the door and/ or maintain it in a closed position.

In the drawings, FIGURE 1 is a side elevation view of the outer portion of the dipper stick of an excavating shovel having a dipper connected thereto and provided with a dipper door and toggle linkage embodying the invention.

FIGURE 2 is a bottom plan view of the dipper taken on line 2-2 of FIGURE 1.

FIGURE 3 is similar to FIGURE 1 and shows a second embodiment of the invention.

Referring to the drawings, an outer portion of an eX- cavator dipper stick is shown at 11 having a shovel dipper 12 pivotally connected at 13. A pair of pitch brace links 14 are connected between the dipper stick and the dipper to maintain their predetermined relative positions. A dipper door 15 is hingedly connected to the rear portion of the dipper by means of hinge pins 16 received in aligned openings in the dipper and door.

To maintain the door in a closed position, as shown in solid lines in FIGURE 1, an over-center toggle linkage is provided at the rear of the dipper door and connected between the door and a pivot which is fixed in relation to the dipper. To provide a more balanced construction, a pair of such toggle linkages may be used, each being spaced equidistantly from the longitudinal center line of the door as shown in FIGURE 2.

The toggle linkage comprises a pair of toggle levers I7 and 18, the lever 17 being pivotally connected to the rear of the dipper at 19 and the lever 18 being pivotally connected at 20 to the door at a point removed from the door pivot, hinge pin 16. Pivot 19 may be carried by the dipper stick so long as the pivot is fixed in relation to the dipper door hinge pin 16. FIGURE 3 discloses the 3,59,793 Patented Get. 23, 1962 second embodiment of the invention in which pivot 19 is carried directly by the dipper stick by means of a. supporting lug on the dipper stick 11, rather than being carried indirectly by means of a lug on the dipper 1.2 as shown in FIGURE 1. So long as pivot 19 and binge pin 16 have relatively fixed positions, the linkage will operate satisfactorily.

The toggle levers 17 and 18 are pivotally connected to each other at 21, to form the knee joint of the toggle linkage. The toggle linkage is arranged and constructed in such a manner that the center of the knee pivot 21 will move, as the door is swung to the fully closed position of FIGURE 1, beyond a line drawn through the centers of the outer pivots 19 and 20 of the linkage, and the toggle linkage will assume an over-center position. A suitable stop such as 22 is operatively associated with the toggle linkage so that the movement beyond center to the overcenter position may be adjustably limited. The weight of the door will thereby maintain toggle lever 17 in contact with the stop 22, so that the toggle linkage will remain in an over-center, locked position as shown in FIGURE 1. Thus the door will be maintained in a closed position without the need for a latch mechanism normally provided at the front of the dipper door.

To open the door, suitable release means is provided such as the cable indicated at 23 connected to a stabilizing link 24 which is operably connected at 25 to toggle lever 1'7. Movement of the release cable 23 and link 24 to the left, as shown in FIGURE 1, will cause movement of the toggle knee 21 to the right. As soon as the knee 21 has moved beyond center to an over-center, unlocked position, the weight of the door and the contents of the dipper will then swing the door about its hinge pivot 16 to an open position, as indicated by the phantom lines. As the door swings to the open position the pivot 20 of toggle lever 18 will be swung in an are about the door hinge pin 16, thus moving the knee 21 to the position 21a shown in phantom lines. Movement of the knee to this position compresses a spring 26 which will later assist in moving the linkage to an over-center, locked position as the door is swung closed.

To close the door during operation of the excavator, the operator by movement of the dipper stick 11 imparts a swinging movement to the door relative to the dipper so that upon a sudden stopping of the dipper the inertia force of the door will move the door to a closed position. To maintain the door in this closed position, the toggle linkage of the present invention must be in an over-center, locked position. To move the toggle linkage to such a position, the velocity of the door swinging relative to the dipper can be sufliciently high to impart an inertia force to the toggle linkage capable of moving the toggle to an over-center, locked position. To assist the inertia force of the toggle linkage and to maintain the toggle in a locked position a resilient means such as a spring 26 is operatively connected between one of the levers of the linkage and a suitable seat for the spring to serve as a reaction point. The spring seat is carried by the dipper stick, either directly or indirectly through the dipper. Since the knee 21 is moved to the right as the door is opened, causing counterclockwise movement of toggle lever 17, the spring 26 will be compressed. The degree of compression of the spring can be selected by the locations of the toggle lever pivots 19, 20 and 21 relative to the door hinge pivot. As the door is swung to a closed position, the energy stored in the compressed spring will assist the inertia force of the toggle linkage in moving the linkage to an overcenter, locked condition, which will thereby maintain the door in its closed position.

At least one of the terminal pivots 19 and 20 of the toggle linkage is preferably mounted in an adjustable fashion so that compensation may be made for minor variations occurring during manufacture as well as wear of the components of the linkage. As shown in FIGURE 1, the pivot 20 is carried in a mounting bracket 27 which is pivotally mounted on the door by means of a pin 28. The position of bracket 27 and the pivot in relation to the door can be determined by varying the number of shims 29 placed between the bracket and a suitable mounting pad on the door. A retaining means such as bolt 39 will then maintain the bracket 27 and the one terminal pivot 20 in a predetermined, adjusted position.

Having now described and illustrated two forms of the invention, it is to be understood that this invention is not to be limited to the specific forms or arrangements of parts herein described and shown.

What is claimed is:

1. In an excavator having a dipper stick, an open dipper mounted on said stick a hinge pivot on the dipper, and a door mounted by means of said hinge pivot to swing relative to said dipper and adapted to close the bottom of said dipper, the combination of: a first toggle pivot on said door spaced from said hinge pivot; a second toggle pivot carried by said dipper stick and spaced from but fixed in relation to said hinge pivot; a toggle linkage connected between said first and second toggle pivots and comprising a pair of toggle links pivotally connected to each other to form a knee, said toggle linkage being arranged and proportioned in such a manner that, when the dipper door is in a closed position, the knee of said linkage is in an over-center position with respect to a line drawn through the centers of said first and second toggle pivots, and said knee being moved to pass over said center line to an over-center position toward said dipper when said dipper door is opened; and stop means operatively associated with one of said toggle links to limit the movement of said knee after reaching said first named overcenter position, whereby the weight of said door will maintain said toggle linkage in an over-center position with said one of the toggle links in contact with said stop.

2. In an excavator having a dipper stick, an open dipper mounted on said stick, a hinge pivot on the dipper, and a door mounted by means of said hinge pivot to swing relative to said dipper and adapted to close the bottom of said dipper, the combination of: a first toggle pivot on said door spaced from said hinge pivot; a second toggle pivot carried by said dipper stick and spaced from but fixed in relation to said hinge pivot; a toggle linkage connected between said first and second toggle pivots' and comprising a pair of toggle links pivotally connected to each other to form a knee, said toggle linkage being arranged and proportioned in such a manner that, when the dipper door is in a closed position, the knee of said linkage is in an over-center position with respect to a line drawn through the centers of said first and second toggle pivots; stop means operatively associated with one or" said toggle links to limit the movement of said knee after reaching said over-center position, whereby the Weight of said door will maintain said toggle linkage in an overcenter position with said one of the toggle links in contact with said stop; and resilient means carried by the dipper stick and operatively associated with one of said toggle links to urge the knee of said toggle linkage to an overcenter position in a direction towards said stop.

3. In an excavator having a dipper and a door pivotally connected thereto and adapted to swing relative to said dipper and to close the bottom thereof, the combination of a pair of terminal pivots supported respectively on said dipper and said door; a toggle linkage connected between said pivots, said linkage comprising a pair of toggle levers pivotally inter-connected to form a knee, said linkage in operation when the door is open having a first position of said knee off-center with relation to an imaginary line passing through the centers of said toggle pivots and when the door is closed said knee having a second position on the opposite side of said line and oft-center with relation to said line; a stop carried on the dipper and in contact with one of said links when said linkage is in said second position; and resilient means carried on the dipper and operatively associated with said linkage to urge one of said links in a direction towards said stop.

4. In an excavator having a dipper stick, an open dipper mounted on said stick, a hinge pivot on the dipper, and a door mounted by means of said hinge pivot to swing relative to said dipper and adapted to close the bottom of said dipper, the combination of:

a first toggle pivot on said door spaced from said hinge pivot;

a second toggle pivot carried by said dipper stick and spaced from but fixed in relation to said hinge pivot;

a toggle linkage connected between said first and second toggle pivots and comprising a pair of toggle links pivotally connected to each other to form a knee, said toggle linkage being arranged and proportioned in such manner that, when the dipper door is in a closed position, the knee of said linkage is in a first over-center position away from said dipper with respect to a center line drawn through the centers of said first and second toggle pivots, and said knee being positioned toward said dipper when said dipper is opened;

stop means for contacting one of said toggle links to limit the movement of said knee after reaching overcenter position, whereby the weight of said door will maintain said toggle linkage in an over-center position with said one of the toggle links in contact with said stop; and a remotely controlled release means carried by the dipper stick to move the toggle linkage in a direction away from said stop and said knee is moved to pass over said center line to a second over-center position toward said dipper, whereby the door is released to swing about said hinge pivot to an open position.

5. In an excavator having a dipper stick, an open dipper mounted on said stick, a hinge pivot on the dipper, and a door mounted by means of said hinge pivot to swing relative to said dipper and adapted to close the bottom of said dipper, the combination of:

a first toggle pivot on said door spaced from said hinge pivot;

a second toggle pivot carried by said dipper stick and spaced from but fixed in relation to said hinge pivot;

a toggle linkage connected between said first and second toggle pivots and comprising a pair of toggle linkage being arranged and proportioned in such manner that, when the dipper door is in a closed position, the knee of said linkage i in an over-center position away from said dipper with respect to a line drawn through the centers of said first and second toggle pivots, and said knee being movable toward said dipper when said dipper is opened;

stop means for contacting one of said toggle links to limit the movement of said knee after reaching overcenter position, and biasing means operatively associated with one of said toggle links to urge the knee of said toggle linkage to an over-center position in a direction towards said stop.

References @Cited in the file of this patent UNITED STATES PATENTS 665,682 Hetlesaeter J an. 8, 1901 

